Protect Sharks
From 500 known species of sharks, 30% are somehow endangered.
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Sharks are major predators, indispensable to healthy marine ecosystems.
It would probably be difficult to find another animal on Earth that has adapted so perfectly to its environment. The Shark is a unique major predator Among current fauna, the Shark is a member of one of the oldest groups of animals to have outlived the dinosaurs. The oldest sharks appeared more than 420 million years ago. Today, more than 500 species of sharks are known. According to the International Union for Conservation of Nature (IUCN), about 30 % of Shark species are critically endangered, threatened or vulnerable.
Sharks are a large group of cartilaginous fish (Chondrichthyes), belonging to the same family group as Rays and Chimeras. Unlike bony fish, they do not have classic solid bones, but an internal bodily support by flexible cartilage and connective tissues.
Sharks are perfectly adapted to their environment. Source: Pixabay
Sharks primarily live in salt (sea-) water, although there are a few exceptions that occur in brackish waters at the mouths of rivers and penetrate their lower reaches, e.g. Bull Shark and River Shark. Sharks can be found in most seas and oceans on Earth.
Body Composition Sharks are very well adapted to movement in the water. They have a perfect hydrodynamic body shape, which allows them to move very quickly. They range in size from 6.7 inches for the Dwarf Lantern Shark (Etmopterus perryi), a deep-sea species of shark, up to the 40 ft-long giant Whale Shark (Rhincodon typus). Most sharks have 8 fins, but this is not always the rule. There are usually a pair of pectoral fins and a pair of abdominal fins. There can be 1 - 2 dorsal fins, 0 - 1 anal fins and a tail fin, which always has a more elongated upper segment.
Comparison of different sizes of Shark. Source: viaGood
Sharks do not have a gas bladder like other fish. This function is taken over by a huge liver (in large species, the liver can weigh up to 200 lb.), which is filled with a lot of light fat. The liver lifts the Shark as effectively as the gas bladder. In addition, it allows the Shark to change depth much faster than fish equipped with a bladder.
Sharks do not have gills like bony fish. The water flows in to the gills through the mouth and flows out through the gill slits. Some sharks can actively pump water into the gills with muscles. Many species do not have these muscles, and water flows around the gill arches only when the Shark moves forward: the faster it moves, the stronger the oxygenation. Therefore, a Shark that cannot swim suffocates, as oxygenated water stops flowing around the gills.
Did you know… sharks can not escape from a net, because they can't move backwards? That's why they can drown when becoming entangled in nets.
Whale Shark with a diver. Source: Pexels
A Shark's skin is very rough and covered with enamel-like placoid scales, giving the Shark a kind of outer skeleton. Because the scales do not overlap, but touch each other, a number of tiny channels are created between them and the surface of the skin through which water can flow. The water thus easily flows around the Shark's body while swimming and there is no friction to slow it down.
Did you know… shark skin used to be used for sword hilts and for sanding wood?
The Shark’s jaw is unique in the animal world. Ancestors of the present-day Shark had the upper jaw firmly attached to the skull, and this determined the size of their prey. However, as the upper jaw evolved, it became detached from the cranial junction and became mobile. In this way, today's sharks can eat very large prey or pluck large pieces of meat from them. The jaw is controlled by very strong muscles. Researchers have measured a pressure of 3 tons per 2.5 inches in a 9-foot-long Shark (comparable to aprox. 500 lb. per 2.5 inches in a 150-lb human).
Shark teeth are very sharp. They have a triangular shape and are embedded in the jaw in solid connective tissue and arranged in several rows. However, only the first row is functional. Shark teeth have an unlimited ability to regenerate. After wear or damage, the teeth bend forward and fall out, and the next row will take over. The rate of tooth renewal can be 8-10 days, but also several months.
Great White Shark at Isla Guadalupe, Mexico. Source: Wikipedia
Speed Sharks usually swim in the ocean at 1.5 mph and wait for prey, then attack the prey at about 12 mph - the speed of a man running on ground. For comparison, an Olympic swimmer swims at a speed of 5 mph.
The Shortfin Mako Shark (Isurus oxyrinchus) is the speed champion of all sharks. Its top recorded speed is 34.8 mph. However, some sources say that it could reach speeds of up to 60 mph, because it catches Sailfish and Swordfish and these can reach speeds of up to 60 mph. The Mako is also the greatest jumper, as it can jump to a height of more than 20 ft.
Color Individual species of sharks have a nondescript color, ranging from gray to cream, brown, yellow, slate or blue, and often patterned with spots, streaks, marbling or protrusions.
Hammerhead Shark. Source: Pexels
Senses The Shark, as a major predator, has sensory organs at its disposal, some of which are completely unique to animals.
- HearingThe range of shark hearing is up to several miles. Experiments have shown that sharks are even able to hear very low frequencies that humans cannot hear, and that the sources of these low frequencies attract them.
- SmellAfter hearing, smell is the second most developed sensory organ in the Shark’s arsenal. At a distance of 500 yards, a Shark can smell blood in the water and follow the trail to its source. It can detect 1 part of fish extract in 25 million parts of seawater, which corresponds to 10 drops of blood in an average-sized swimming pool.
- Side lineSide line works like a position change detector by registering the slightest quiver of water flow and therefore vibration. In addition, it plays a crucial role in maintaining balance and can be compared to sonar. This system occurs in most fish, including sharks.
- VisionThe Shark’s eye is similar to that of other vertebrates, but is very well adapted to the marine environment. It uses a tissue called tapetum lucidum. This tissue is situated behind the retina and reflects light back, increasing visibility in dark water. The Shark can detect movements 82 ft away in relatively clear water. Some species have nictitating membranes - these cover and protect the eye, especially during attack. Some species, however, do not have this membrane. Instead, some sharks turn the eyes backwards during attack, e.g. the Great White Shark (Carcharodon carcharias).
- ElectroreceptorsSharks have the highest electrical sensitivity of all animals, thanks to the Lorenzini Ampoules in their heads. They use them to detect the electromagnetic field produced by all living creatures. It helps sharks, especially Hammerhead Sharks
Shark senses. Source: viaGood
Did you know… intrauterine cannibalism is known in some Shark species, where the strongest embryos eat their weaker siblings?
Sharks are oviparous, ovovivipary or viviparous, and in the second group, intrauterine cannibalism can occur. The eggs of some species are over 8 inches in size. With the exception of the Bullhead Shark, egg cases are typically rectangular in shape with projections, called horns, at each corner. Depending on the species, egg cases may have one or more tendrils.
The lifespan of a Shark varies by species. Most of them live for 20 to 30 years. But there are exceptions, e.g. the Spiny Dogfish lives for about 100 years and the Greenland Shark can live up to 400 years.
Did you know… unlike many other sharks, the Great White Shark is not a major predator in all its natural habitats? This is because Killer Whales sometimes hunt it.
A signpost warning against sharks. Manly Beach, Australia. Source: Unsplash
Shark Attacks on Humans Sharks have a very bad reputation and people fear shark attacks. In any case, the statistics show that you are more likely to be killed by lightning than by a shark attack. For example, in the coastal states of the USA, 1 970 people died from lightning strikes between 1959 and 2010 (i.e. 37.9 per year). During the same period, 26 people died after shark attacks (i.e. 0.5 per year).
Of the hundreds of known sharks, only about a dozen are dangerous, and only three species are responsible for most attacks on humans: the Great White Shark (Carcharodon carcharias), Tiger Shark (Galeocerdo cuvier), and Bull Shark (Carcharhinus leucas). Yet these attacks are not aimed at humans, but due to sharks’ confusion of humans with their natural prey.
Peter Benchley, author of the famous short story Jaws, said he regretted writing about sharks. "What I now know, which wasn't known when I wrote ‘Jaws’, is that there is no such thing as a rogue shark which develops a taste for human flesh," Benchley told the Animal Attack Files in 2000.
About 11 417 sharks are killed every hour - that's 100 million per year!
What are the main threats sharks are facing? All of them are caused by humans!
Commercial Fishing The biggest threat to sharks is overfishing. They are hunted for:
- Fins are sought after in both traditional Chinese Medicine and Gastronomy, for traditional Shark Fin Soup, which is considered a delicacy in East and Southeast Asia. **Finning **(removing shark fins while the rest of the body is thrown back into the ocean) is responsible for 26 to 73 million shark deaths per year!
- Shark liver oil is used in deodorants, sunscreens, lipsticks, lip balms, vaccines and other supplements.
- Shark cartilage is marketed as a health supplement, although there is no clinical evidence that it is effective against arthritis, rheumatism, hemorrhoids or even cancer.
- Shark skin is used to make luxury items, such as purses or shoes.
- Shark jaws and teeth are sold to tourists. Bycatch Tuna fishing in particular has a major impact on sharks, as sharks become collateral victims of entanglement in fishing nets. Trawling thus decimates bottom-dwelling shark populations.
Climate Change and Habitat Degradation All sharks depend on healthy ecosystems and an abundance of food. Habitat degradation includes the effects of climate change, pollution and the destruction of areas such as mangroves and cliffs.
Strict laws can improve the survival prospects of sharks.
Before buying any product, make sure it does not contain any shark ingredients. By boycotting shark products, you will reduce the market demand, which will cause companies to stop killing sharks to produce such goods. What else can be done?
Prohibit the removal of fins at sea Finning is a barbaric practice of cutting the fins of a live shark and throwing the rest of the body into the sea. Laws need to be changed, so that these cruel hunting practices are not possible and are punishable by Law.
Fight for more Sustainable Fishing Many sharks get stuck in nets as bycatch. It is necessary to review laws and to upgrade fishing vessel equipment to end deadly fishing.
More rigorous Shark Protection New laws need to be enforced to protect endangered Shark species. Along with the laws, it is necessary to control fishing vessels and monitor fishermen's behavior.
Monitoring of Sharks Satellite tracking of sharks serves to better understand shark migratory routes and their behavior in the open seas. It can also serve as a protection against the attacks on humans by the most dangerous sharks, without having to kill them.
Cleansing the Oceans An increasing volume of trash is entering the oceans and this trend must be stopped. Tougher waste management policies are necessary in all countries, as well as active support for ocean cleansing projects.
Education As it is very difficult to push for changes in shark protection, it is necessary to ensure better awareness of this issue in the first place. Many people still think that there is an infinite number of sharks and so there is no need to worry about their future.
Everyone can get involved. How can YOU help?
Do not use Shark Products Shark Fin Soup is a great gourmet experience, but remember that every serving means a dead shark, having cruelly had its fins removed while still alive, for your plate! However, there are also other shark parts used.
Reduce your Consumption of Seafood Commercial fishing significantly reduces the population of food resources and sharks also die as collateral damage of commercial fishing. By simply reducing your own consumption of seafood, you can reduce the number of sharks killed each year.
Recycle Waste is a threat to the entire marine ecosystem, and the Shark is no exception. Trash (e.g. plastic) is consumed by the marine species which make up sharks’ food. As a result, this trash also reaches sharks, causing them illness and subsequent death. With each bit of recycled waste, this risk is reduced.
Spread Awareness Social networks are a powerful tool and you can spread information about the situation of the Shark to your friends and acquaintances.
